Field of the Invention
The invention relates to a safety needle device which is mounted onto an outer medical instrument and which is a disposable device, assuring a user protection against an accidental or intentional prick with a needle before and after a proper use of the device in compliance with the purpose for which it is intended, and which device can be provided with an adjustment of the insertion depth of the needle into a patient's body.
State of Art
There are known safety needles serving to introduce into the patient's body a dose of a cosmetic and/or pharmaceutical composition which is being drawn out of a container disposed in an injection device cooperating therewith, which usually comprises a mechanism for the dose adjustment. The safety needle should be a disposable device, replaceable after every administration of a medicine dose, for example, insulin, human somatotropin or medicines against osteoporosis, and should be safe for circumambiency, that is protective against an accidental injury of the user both before its primary use, and after, that is protective against an accidental injury by the contaminated needle used earlier. After use safety needles are retracted from the patient's body and removed from the medical instrument after single use in order to minimize impurity of medicine closed in the container and to prevent a re-use of the needle. The user of a safety needle device is a medical professional, or another caregiver, but also more and more frequently an individual patient making a choice of the medicine dose, following doctor's prescriptions, and adjusting the medicine dose, for example insulin, respectively to a result of a blood sugar level test performed by himself, and then making by himself the injection of the medicine dose. However, a danger of a needlestick injury relates also to every person who may be in touch with the needle after it has been thrown away by the user, including the activities of packaging of the devices used, safeguarding, transport and the process of utilization. As for an angle at which the needle enters the patient's body, it has been observed that the injection “at a sharp angle” is very often practiced in health centers, in which needles with a nominal length of 8 mm are used. In the case when patient's predispositions require an application of a shorter needle, the hospital staff applies an injection technique “at the sharp angle”, which results in different actual insertion depths depending on the needle inclination. Such a method, of making the injection “at the sharp angle” to the patient's body surface, is the preferred and convenient method also because of ergonomic reasons. However, in case of hypodermic injections of insulin or preparations used in cosmetic medicine, for example anti-wrinkle agents, performed by needles or particularly thin cannulas, the injection technique “at the sharp angle” applied by using known safety needle devices often leads to bending of the needle during and in the course of its insertion into the skin. Such a warped needle precludes the proper and precise application of the administered substance and may be dangerous for the patient.
Known safety needle devices have complex structure requiring precise cooperation of many component parts, which is the reason why these devices are not only costly but also, because of their complexity, susceptible to damages and faulty in operation, which may be dangerous for the user. In known safety needle devices, observing a needle end from the patient's side by the user before the use of the device is neither easy nor convenient, and in most cases impossible. Likewise in the course of preparing the needle for use, which requires evacuation of air lingering in the bore of the needle. In the known devices adequate preparation of the device for the use is not possible.
The known safety needles do not provide the user with the comfort of checking whether the appearance of the needle is correct, of checking its alinement and patency before the use as well as checking whether the needle bore is full of liquid which is to be administered to the patient, wherein the use of the device with a defective needle or the fact of introducing into the patient's body a certain amount of air, because of the incorrect preparation of the needle for the use, causes a serious threat for the patient.
The safety needle, especially its end from the patient's side, should be shielded before its primary use but also, immediately, after its withdrawal from the patient's body, still before the removal of the whole safety needle device from the medical instrument. At the same time, the needle should be guided in the course of the use of the device in such a manner as to enable its insertion into the patient's body “at the sharp angle” simultaneously assuring the correct insertion and injection as well as safety for the patient, independently of parameters of the needle or cannula.
It is desirable to design a cheap safety needle device of simple structure precluding a subsequent use of the device after its single use.
From patent description no. U.S. Pat. No. 7,815,611 B2 there is known an insulin safety needle device comprising a hub for fixing to an injection device, a needle mounted in the hub with one end for insertion into a container with insulin and with another end adapted to the injection into the patient's body, a protecting shield surrounding the needle and movable along its axis, which is being locked after the use of the device in the position, in which it protects a needle tip, and further the device comprises a catch pawl attached to the hub and called a clip member, with resilient side tongues, and a spring disposed inside the protecting shield. The resilient side tongues of the catch pawl, starting from the moment of assembling of the safety needle device until the moment of the device activation, are biased, which may, as a result of long-lasting storage of the device or transportation, cause a permanent deformation of the side tongues and prevent the locking of the protecting shield from activating after the use of the device, and thereby impending the needle protection. The threat is the more serious as the side tongues of the catch pawl are structure elements of rather small dimensions and as such they undergo deformations more easily. In this device, the spring acts by being expanded between the protecting shield and the catch pawl with the resilient side tongues. In this way, the spring acts directly onto the locking means additionally increasing their deformation and having an adverse impact on the locking effectiveness. If the needle is not correctly protected after the use of the device, such a device may be re-used. In this safety needle, the user has an easy access to the side tongues of the catch pawl, which gives him or her a possibility to unlock the protecting shield easily and to expose the needle, for the purpose of its repeated or multiple use. The structure of this safety needle does not enable the assessment of the state of the needle including its patency, which is a discomfort for the user and may even result in not administering the medicine to the patient because the user is not able to assess whether the flow through the needle during the injection is effective or not. The angle, at which the device is applied to the patient's skin and the injection is made, is another issue. The protecting shield in this device has the end from the patient's side of a relatively big surface, which forces the injection of the needle at the right angle to the patient's skin. Every possible change of the device arrangement relative to the patient's body surface towards the angle different than the right angle causes a significant shortening of the declared insertion depth and thereby a defective injection, and a necessity to perform a corrective injection to supply the respective medicine dose, and this in turn requires a further or another precipitated injection, and the use of another disposable device. In the described safety needle device, the side tongues of the catch pawl, after locking the protecting shield in the position shielding the needle after the use of the device, function also as indicators of the use of the device. However, the feature that the indicator of the use of the device is situated on locking means and is accessible for the user, who may easily change the indication of the state of the use of the device, is an undesired feature.
From patent description no. U.S. Pat. No. 8,062,265 B2 there is known an insulin safety needle having a hub enabling the attachment of the safety needle to an injection device, a cannula mounted in the hub with one end puncturing a container with insulin and with the other injection end, a protective shield slidable to a position preventing a re-use of the safety needle. The movement of the protecting shield along the hub is associated with its rotational movement which is forced by a specifically designed opening. The rotational movement of the protecting shield is an undesired movement because the shield contacts directly with the patient's skin during the injection and a friction thereon may produce an additional impediment to a correct operation of the device, as well as may cause the patient additional unpleasant and undesired impressions. In the described safety needle it is required to remove, before the use, an additional component part shielding the needle and protecting against an accidental actuation of a blocking. As soon as it is removed, there is a possibility to cut oneself with a non-protected cannula repeatedly because the actuation of the blocking of the protecting shield is performed only when a significant determined length of the cannula is exposed. This safety needle involves the necessity to use a metal spring pushing out the protecting shield because during the storage period of the product before use, the safety needle is subjected to load, and the spring made of plastic would deform permanently, and would not be able to cause the full movement of the protecting shield necessary to protect the needle. The application of the metal spring is a drawback because of economical and recycling reasons.
Patent description no. EP 2,090,326 discloses a safety needle with a protecting shield, the blocking of which in a position preventing a re-use of the needle requires meeting two conditions. Firstly, the injection has to be performed with a full possible depth so that the protecting shield is able to reach a container with a spring. Secondly, the injection has to be performed with an adequate force so that the protecting shield is able to break off safeguard locking against self-actuation in the container with the spring. In this safety needle device there is a possibility to make repeated accidental or intentional injections provided that injections are not made with full depth or are made with a force insufficient to actuate the blocking. A necessity to exert onto the protecting shield a big additional force indispensable to actuate the blocking may cause a discomfort for the patient, especially when he or she makes the injection on their own. This safety needle requires the application of the spring made of metal because during the period of product storage before use this safety needle is subjected to a load, and the spring made of plastic in this mechanical system would deform and as such would not cause a full movement of the protecting shield necessary to expose the needle. The metal spring is undesirable because of economical and recycling reasons.
From patent description no. U.S. Pat. No. 5,944,700 there is known a pen needle with an adjustable insertion depth. The pen needle comprises a hub attaching the needle to the pen, a cannula mounted in the hub with an end pricking a container with a medicine and with an injection end, and an additional component part rotatably coupled with the hub. To adjust a desired insertion depth, the user has to cause this component part to rotate around the cannula by manipulation close to a tip, which puts him or her at risk of hurting themselves. Moreover, the necessity to perform a rotational movement of some component part within the needle device to the pen is mistakable for the patient because it may suggest adjustment of the value of the medicine dose in the pen, with which it cooperates. Such a structure may create a danger for the patient, particularly for the patient in the state of serious stress or weakness.
Further, the publication of application description no. US 2011/0295204 A1 discloses a tube assembly for controlling length of a syringe needle, which comprises an additional component part coupled to the needle for the purpose of adjustment of the insertion depth. The tube assembly for controlling the active length of the needle, after being used, may be re-coupled to a new needle and re-used. The assembly requires, however, while adjusting the insertion depth, manipulation in the vicinity of a non-protected needle tip. Further, the manipulation is performed by a rotational movement of the component part of the tube assembly, which may suggest the adjustment of the medicine dose to be injected.